jquery ui中的ui.draggable是什么意思

Question

var $photo = $("#photo");var $trash = $("#trash");$("li").draggable({  revert: "invalid",  helper: "clone",  cursor: "move"});$trash.droppable({  accept: "#photo li",  activeClass: "highlight",  drop: function(event, ui){    abc(ui.draggable);      //ui是什么东西，ui.draggable又是什么意思  }});

Answer 1

如下图所示：